There was a time when a person had to rely only on his eyesight during hunting, the Olympics, or military missions. Men had to spend many hours practicing to hit the target, performing monotonous movements, and trying new techniques, positions, and distances so that their bodies and eyes could remember what to do at the crucial moment.
But human nature is designed to improve its life and develop its field of work continually. Thus, today's technology can provide us with a wide variety of devices so that during the above activities, we can hit the target accurately with any weapon, from any distance, even in any light. Electronic optics, with a wide range of different functions that can see day and night, with varying grids of marking—all this is your guarantee of success.
However, despite all the modern modifications, you should consider conventional red dot optics, i.e., collimator sights with this marking. What is it? How does it work? What are its advantages and disadvantages? Today, we will talk about all this.
What is a Red Dot Optic?
First, let's start with the fact that a red dot optic should not be confused with a laser sight.
A red dot sight is a general classification for a reflex type of sight for firearms and other devices that require aiming, giving the user an aiming point in the form of an illuminated red dot. The standard design uses a red light-emitting diode (LED) in the focus of a collimating optical system that generates a dot light grid centered on matching the weapon to which the sight is attached, regardless of eye position (almost parallax-free). They are readily available and accessible for target shooting, hunting, police, and military applications. In addition to their use of firearms, they are also used on cameras and telescopes. On cameras, they are used to photograph aircraft, birds in flight, and other distant, fast-moving objects.
A collimator sight is widely used in various weapons - large-caliber pistols, shotguns, and automatic weapons with a high rate of fire. This type of sight has increased accuracy, which helps to make effective shots and can also be used by people with visual impairments. People suffering from astigmatism, myopia, and other visible diseases can use a collimator sight. Using the optics of this class, there is a chance to quickly shoot any weapon, even if the average aiming point is offset.
How does a red dot sight work?
The principle of this technology has been introduced previously. The collimator sight was invented in 1817 by an Irishman named Howard Grubb. He is considered the father of the telescope and the one who helped develop the periscope. He correctly assumed that this type of optic could help make aiming faster and posture more accurate. That is why, even in our time, many supporters still support the red dot sight.
The typical configuration for a red dot sight is an inclined spherical mirror reflector with a red light-emitting diode (LED) at the focal length of the axis. The mirror has a partially silvered multilayer dielectric diachronic coating designed to reflect only the red spectrum, allowing it to pass through most other light sources. The LED used usually has a deep red wavelength of 670 nanometers, as they are very bright, have high contrast with a green scene, and work well with a dichroic coating as they are near one end of the visible spectrum. The size of the dot generated by the LED is controlled by the aperture hole in front of it, made of metal or coated glass.
The principle of operation of a collimator depends on its projection system. Collimator sights can be divided into two types. Namely, reflex and holographic.
The classic version will work as follows. An LED hidden inside the body emits light toward the lens, which has a reflective, translucent coating on its inner surface. The light rays are reflected from the lens surface towards the observer and form a parallel beam. Due to the parallelism of the rays, the pupil's displacement relative to the optical axis of the sight will not cause the mark to move off the aiming point.
Holographic sights are a separate type of sighting device, but for the user, they do not differ much from reflex red dot sights. Instead of a standard mark in the lens plane, the observer sees a hologram behind the glass: it seems to be "hanging in the air" at 50-100 meters from the observer.
A holographic sight contains a laser emitter that generates polarized light. The laser beam emitted by the diode is directed to several reflectors, including a "rectifying" collimator. Parallel light beams then hit the diffraction grating and, after interacting with it, illuminate the 3D image of the reticle embedded in the sighting lens. The holographic film with the reticle acts as a reflector and directs the image toward the shooter's eye, thus forming a hologram.
Unlike reflex sights, holographic sights have no coating on the lens: nothing disturbs the light path through the lens in the plane in which the image is formed. You can see the target clearly, while the reticle is superimposed on your field of view.
Different Types of Red Dots
Another criterion that distinguishes this type's sight is its design's peculiarity. This is how we distinguish between open and closed red dot sights.
Closed sights are a combination of lenses enclosed in a tube; the body has a closed cylindrical shape. The radiation source is located inside the housing, thus reliably protected from external influences (dust, moisture, etc.) and mechanical damage. In expensive models, the accommodation is often filled with nitrogen to ensure complete waterproofness of the structure and eliminate the risk of fogging of the optics from the inside. Also, the advantages of a closed collimator include a more robust and reliable design. Such scopes are comfortable to operate and are much less afraid of dirt. Closed reticles are preferred for bull's-eye shooting, as this design allows you to focus more on the target since the view is slightly cut off by the body, unlike an open reticle.
Open collimators have an open design with a single lens. Such sights are even more compact and lightweight. In addition, available collimators are characterized by a wider field of view, which plays a vital role when shooting at fast-moving targets. The radiation source in such specimens is usually not protected from the external environment; only in some models can the emitter be hidden behind a special protective glass that prevents dust, debris, and dirt from entering. By the way, geographic sights are a subcategory of open collimators, an essential feature of which is the complete absence of parallax. It is convenient to look through an open collimator with one eye without covering the other. All you need to do is align the dot with the target and shoot.
In addition, it is essential to emphasize that the red dot on the collimator sights is only a type of reticle, which is the most common. The reticle's size is often indicated in MOA (Minute of Angle). A 1 MOA reticle allows you to hit a 1-inch (2.54 cm) diameter circle at 100 yards (91 m). When shooting at longer distances, the area of the process covered by the 1 MOA increases and decreases as the distance decreases.
In other words, the smaller the red dot, the more accurate you will be at extended ranges with this reticle. But then why do riflescope manufacturers produce reticles with larger dots (up to 10-12 MOA) or more complex reticles? The fact is that in different circumstances, shooters need not only accuracy but also speed of aiming, ease of target acquisition, the ability to take ballistics into account, adaptation of the reticle to changes in illumination, etc.
The larger the reticle dot, the easier to shoot in a sweeping motion and the faster you can aim at a moving target. As a rule of thumb, 4-8 MOA red dot sights are recommended for pistols and carbines and 1-3 MOA for rifles.
When you choose a collimator sight, you will also pay attention to the type of power supply that the collimator emitter requires. The vast majority of them operate with rechargeable batteries. However, depending on the emitter parameters, operating conditions, and type of power supply system, the operating time of collimator sights without battery replacement differs significantly. For different models, it ranges from 100 hours to 30-50 thousand hours.
There are also models on the market that operate on a rechargeable battery and even energy-efficient collimators with a hybrid power system - from a battery and a solar panel on the body. The development of monocrystalline solar cells has led to the emergence of fully autonomous devices: modern "hybrid" collimator sights can operate without batteries, solely on solar energy.
The pros and cons of red dot sights
Red dot sights have many advantages. First of all, they are compact. This is a small tool that you can take everywhere. Even if you have a rifle scope, you can take this option with you because it will only take up a little space in your bag and help you achieve your desired goals.
Red dot sights are very comfortable to use and ergonomic. We have already mentioned above that they will be helpful for people who have vision problems, and glasses will not be a hindrance. Because there is no need to focus on three points - the reticle, the fly, and the target you want to hit. For some people, this kind of aim can be physically challenging. Instead, a collimator invites you to focus on a bright dot superimposed on your target.
Another advantage of collimators is that they allow the shooter to control the surrounding space better while aiming. Since the shooter does not experience the "tunnel vision" effect, is not focused on the front sight and rear sight, is not limited by the scope tube, and looks at the luminous dot, he does not lose his peripheral vision and can see everything that is happening around him. This can be very valuable in backcountry hunting when the animal can come out unexpectedly and not from where you expected.
Collimator sights can be beneficial for shooting at close targets. It doesn't matter if it's a target in a sporting event, an animal on a hunt, or just bottles and cans during recreational shooting. Instead of wasting precious seconds aligning the fly and the target, you can quickly point a bright marker (dot or something else) at your target. Moreover, regardless of how quickly and from what position you align the dot with the target, you have already aimed and are aiming accurately and correctly. Modern collimator sights have virtually no parallax problem.
They are also capable of providing noticeable contrast in low-light conditions. You may not be able to see the fly at dusk, dawn, or in cloudy weather, even if you don't have any particular vision problems. At the same time, a bright collimator reticle marker can help you successfully hit the target. The luminous dot will indicate everything clearly and accurately. Other advantages of collimator sights include a reasonable price and durability.
As for the disadvantages, users mainly mention the phenomenon of parallax. However, modern models are gradually getting rid of this flaw during production. A collimator sight is also unsuitable for those who value zoom when aiming.
Do red dot sights work at night?
Just a quick summary. Yes. Technically, you can use it in the dark. However, it will also depend on whether you can see your surroundings. After all, you only point the red dot at the target. If you can't see it, it's unlikely to be helpful.
In general, a red dot sight will come in handy. Of course, a riflescope is better for long distances, especially when you need more time to aim and fire. But buying heavy multi-lens optics simply does not make sense for shooting on the move at not-too-distant targets, for mounting on short-barreled weapons or multi-compression airguns.